My alarm clock ran out of battery and didn't go off but luckily my cell phone alarm woke me up. We left the Guest House at 5:45 in the morning and walked a little way on the main road to catch a tok-tok. It costs 150 rupees to the station and we got to the station just after 6am.
There were some shops in the station building which sold snacks and lunch
boxes. I bought a package of dal curry with rice and found it didn't come
with a spoon. Local people squeeze rice and curry together with their right
hand and eat it with no difficulty. We used the Guest House's spoon when
we stayed there but in the train there was no spoon. We started to eat
curry and rice with our fingers but we dropped it a lot and soon gave up.
Bringing "your own spoon" is essential in Sri Lanka. 
No train came even though it was well past the scheduled departure time.
It seemed to happen often since nobody looked worried. In the end, the
train came 30 minutes after the scheduled departure time.The only first-class room had double seats and was situated ahead of the third-class cars. The second-class car had double seats, too. The fee for first-class is double second class but it is not worth paying double. The seats were reserved but most passengers didn't care about seat numbers and actually the seat numbers were hard to find. The train was about 80% full when it left Anuradhapura. Some people got on at stations on the way and the train became almost full.
From the train window, we saw nothing but paddy fields and sometimes towns.
Just before noon, we arrived at Colombo Fort station.
From here, another line connects to the Bandaranaike International Airport but the next train was scheduled for hours later. So we went out of the station and took a taxi.
We arrived at the airport at around 1pm. As the departure time of our airplane was midnight there was a long wait ahead. We bought bread and a samosa at a shop and the shop clerk gave us a small piece of chocolate instead of 10-rupee change. We also bought a bottled water at another shop and this time the shop clerk returned Chit Chat which is an immitation of Kit Kat. Here is Sri Lanka. Fortunately our airplane departed on schedule. The good thing is that the plane was only about 20% full so there was plenty of room to stretch.
The end